Crypto price API: real-time prices for AI agents

Real-time crypto price API for AI agents and apps: USD prices and 24h change for up to 10 symbols per call, billed $0.001 USDC per call through x402 on Base. No signup, no API key.

Endpoint

POST https://apisphere.us.ci/api/v1/crypto-price returns the current USD price and 24h change for each requested symbol. A plain GET only advertises the x402 payment challenge - send data over POST.

  • Price: $0.001 USDC per call, settled on Base through x402.
  • Freshness: results are cached for 60 seconds (REAL_TIME).
  • Symbols are case-insensitive and returned uppercased.

Request fields

Send a JSON body. Invalid bodies return 400 with field-level details.

  • symbols (required): 1 to 10 strings, each 1 to 20 characters - e.g. ["btc", "eth"].
  • currency (optional): up to 10 characters, defaults to "usd".
Paid request
curl -X POST https://apisphere.us.ci/api/v1/crypto-price \
  -H "Content-Type: application/json" \
  -H "X-PAYMENT: <signed-payment-payload>" \
  -d '{"symbols": ["btc", "eth"]}'

Response

A 200 response maps each symbol to its price, 24h change, and last update time, plus a meta block with the cache state and request id.

  • 400 - invalid symbols or currency (details in the response).
  • 402 - missing or invalid payment.
  • 429 - rate limited; honor Retry-After.
  • 502 - upstream provider error; the same request is safe to retry.
Example 200 body
{
  "BTC": {
    "price": 80303,
    "change24h": -0.97,
    "lastUpdated": "2026-09-20T07:13:30.000Z"
  },
  "meta": {
    "cache": "miss",
    "request_id": "7f3a9c2e-1b4d-4f6a-8c2e-9d1f5a3b7c4e"
  }
}